A vehicle information notification device is mounted in a vehicle and notifies various pieces of information which are acquired by the vehicle to the driver. The information notified to the driver includes the driving state and the surrounding conditions of the vehicle. For example, when the vehicle enters an intersection, the vehicle information notification device notifies warning information to the driver to call attention to other vehicles. The information notified to the driver in this way includes the driving state and the surrounding conditions of the vehicle which are notified to the driver in real time and is used for subsequent driving actions in many cases.
Further, there is a possibility that in the case of using a technique to display information on a vehicle-mounted display, such as a center display, and notify the information, as means of notifying information to the driver, the driver's attention is directed to the vehicle-mounted display, so that the forward visibility of the driver is restricted. Therefore, the means of notifying information to the driver is typically one using a sound. The information notified to the driver is used for the driver's driving action in many cases, as mentioned above, and it is therefore necessary to certainly notify the information to the driver in real time.
On the other hand, in the case of making a notification using a sound, the notification sound is buried in ambient noise and it becomes impossible for the driver to recognize the notification sound not only when an operation failure occurs in a sound output system, such as a speaker or an amplifier, and the notification sound cannot be outputted, but also when the surrounding noise level is high. Therefore, the vehicle information notification device needs to have a function of performing a self-diagnosis of whether the vehicle information notification device can make a notification precisely.
For example, patent reference 1 discloses a device that performs a self-diagnosis of whether or not a notification sound is outputted normally by performing sound output of a predetermined acoustic loop back signal, and collecting this acoustic loop back signal. In order to avoid an erroneous determination due to the mixing of external noise in the acoustic loop back signal, this device determines that an abnormality has occurred when the number of detections of the abnormality becomes equal to or larger than a predetermined number after repeatedly performing the above-mentioned abnormality diagnosis two or more times. In this way, the device achieves an improvement in the reliability of the abnormality diagnosis.